2o6 JORDAN. [Vol. VIII. 



ules are conspicuous by their absence, and this absence of 

 pigment, or the presence of the vesicular debris, or both, 

 unquestionably gives the appearance of the large light area 



(Fig. 3)- 



Schultze {l.c.y p. 205) seems inclined to adopt the view that 

 the absence of pigment in this region is due to the fact that 

 the germinal vesicle once filled this area, and that, notwith- 

 standing the vesicular atrophy, the pigment granules still 

 remain pressed out in a ring. It does not seem to me, how- 

 ever, that this explanation, simple as it is, is quite satisfac- 

 tory. Since yolk granules are found in considerable numbers 

 throughout this region, one is tempted to ask, if the yolk 

 granules have thus invaded the former site of the vesicle, 

 why not pigment granules also } The mantle of pigment 

 granules that often envelops the spindle, and is particularly 

 dense at the two poles, is a partial answer to this question. 

 It shows that pigment granules have entered the vesicular 

 region along with the yolk spherules, and have been attracted 

 to the close neighborhood of the spindle. The comparative 

 lack of pigment in the surrounding territory may well be due 

 in part to this concentration around the spindle. But this 

 cannot account for all the phenomena. Shortly after the Q.gg 

 is laid the pigment begins to show a more even distribution 

 over the upper hemisphere of the ^gg, and eventually regains 

 its original uniformity of disposition. This takes place in a 

 few hours. Now, since the white spot has in some cases 

 remained practically unchanged for at least forty-eight hours, 

 — as I shall show later — and since during all this time the 

 outer ring of pigment has been forced to keep its distance, 

 it cannot be mere lapse of time that brings about the redis- 

 tribution of the pigment after the Q.g% is laid. The principal 

 events of the period that follows the deposition of the (t'gg 

 are changes in the nuclear substance (including by that phrase 

 the whole spindle-chromosome mass), and the migration of 

 the female pronucleus away from the periphery. Since the 

 female pronucleus carries with it in this migration a com- 

 paratively insignificant amount of protoplasm, one is led to 

 infer that it is either the nuclear metamorphosis or the nuclear 



